| 摘要 |
351,750. Dynamos and motors combined for transmitting power. AKT.- GES. BROWN, BOVERI, ET CIE, Baden, Switzerland. July 7, 1930, No. 20501. Convention date, Aug. 3, 1929. [Class 38 (iv).] Regulation, automatic.-A vehicle drive comprising an internal-combustion engine (in particular a Diesel engine) and a main generator excited by a constant voltage obtained from an auxiliary generator, and controlled by speed regulation of the prime mover and by a resistance in the field circuit of the main generator, has additional means controlling the field resistance in dependence upon the armature current only of the generator. Overloading of the engine may thus be prevented. Associated indicating means may assist the driver in correctly adjusting the field in relation to the speed-setting of the prime mover. As shown in Fig. 1, relays p, each responsive to a different generator current, interrupt the circuits of field resistance contactors q, which otherwise are under the control of a drum s so that the driver cannot increase the excitation above that appropriate to a given generator current. Indicator lamps may be associated with the drum s and auxiliary contacts on the relays p to show when the generator is fully loaded. The driver may be permitted to increase the excitation to an overloading extent when the prime mover is set to full speed by means of a pushbutton rendered inoperative in other controller positions by a contact member on the controller. In the modification according to Fig. 2, the field resistance controller s is driven by a fluidpressure servomotor u, the valves 1, 2 of which are operated by auxiliary currents through contacts of relays 3, 4 so arranged that with both contacts open the controller is advanced and the field strengthened, with that of relay 3 open, the controller is held stationary, and with the contacts of both relays open the field is reduced. These relays respond to definite values of the generator armature current, relay 3 lifting at a somewhat lower current than relav 4. The controller is driven to defined positions corresponding to the various resistance steps by means of auxiliary windings on the relays which carry different currents in different controller positions as determined by an auxiliary drum w and resistances x. The speed controller b, exciter field rheostat and a generator field switch b are all operated by a hand-wheel k, and in the lowest speed position an auxiliary resistance r<1> is inserted in the generator field for shunting operations. Additional field resistance steps may be controlled by the hand-wheel k, to provide subsidiary driving positions. The generator field control may work in dependence on the setting of the speed control for instance by means of additional resistances in circuit with the relays 3, 4 which are short-circuited at low-speed settings. |
